Refrigerating machines



July 21, 1964 A. F ENEMARK 3,141,603

REFRIGERATING MACHINES Filed Nov. 28, 1962 United States Patent "ice,

3,141,6h8 REFREGERATING MACHINES Arne Fromm Enemark, Sonderborg,Denmark, assignor to Danioss A/S, Nordhorg, Denmark, a company ofDenmark Filed Nov. 28, 1962, Ser. No. 240,628 Claims priority,application Germany Nov. 28, 1951 4 Claims. ((31. 230-232) Thisinvention is concerned with a motor compressor of the type used in smallrefrigerating machines, e.g., machines adapted to be enclosed in ahermetically-sealed capsule, and the invention is more particularlyconcerned with the compressor and related portions of such machines.

Refrigerating machines of the type used in domestic refrigerators areproduced in large quantities and, therefore, structural simplificationsand efficiencies can reduce production costs considerably. It has beenproposed to unite components adapted to carry out different functions ina single unitary assembly e.g. by casting the motor support integrallywith the cylinder, or by casting the cylinder with the muffler chambers.

It is an object of this invention to provide a construction which makesit possible to realize a major reduction in production costs.

According to the invention this object is realized in a componentcomprising at least the motor support and the cylinder integrally castas a precision cast unit, the cast blank having holes for securing meansand connecting channels so that further machining of the component isnot necessary. Only a finishing treatment of the interior surfaces ofthe bearing and of the cylinder defined in the cast unit will benecessary. whereas it previously was necessary to carry out a number ofWorking procedures to obtain a finished component e.g. the boring ofbearings, cylinder, all connecting channels, and holes for securingmeans, it is, according to the present invention, necessary to carry outonly two working procedures, viz., polishing of the interior surfaces ofthe bearing and of the cylinder. The assembly line, on which all theseprocedures previously were carried out in an automatic sequence, canthus be shortened. Only one machine is necessary on which tools placedat right angles to each other carry out the polishing of the bearing andof the cylinder.

Thus, in accordance with the invention, not only are the number ofworking procedures substantially reduced, but general production costsare minimized through shorter travel time on the assembly line, andpurchase, erecation, and maintenance costs are also substantiallyreduced.

Precision casting is well known and comprises chill casting and pressuredie-casting. Primary casting alloys are various known aluminum and zincalloys, but in some cases, where the size and use of the devicedictates, alloys based on magnesium are suitably used.

The accuracy of precision casting not only makes further finishingunnecessary but, due to the hardness obtained by reason of thehomogeneity of the cast metal, the use of thinner walls is madepossible, which decreases the weight and quantity of the material used,thus further reducing costs.

Precision casting can be carried out with such accuracy that themeasurement corrections of parts to be polished will be less than 0.1mm. This polishing can be carried out by means of precision boring,precision grinding and/ or honing, but it can also be carried out bymaterial compression, e.g. by knurling, which at the same time improvesthe surface of the sliding faces. Aluminum can, in this manner, bereduced to a surface roughness of 0.2 to 2 and a hardness correspondingto that of steel.

The tolerances obtained correspond easily to cylinder borings of thistype, and previously were obtainable only by repeated borings andsubsequent honing.

In refrigerating machines it is of decisive importance that theindividual components be maintained exactly in proportion to each otherand that they be kept in this position permanently. In particular, thisis important in assembling of the motor support and the stator stackbecause of the airgap of the motor must be set very accurately.

Another object of this invention is thus to provide a constructionwherein securing means, other than those heretofore used, can beutilized for assembling individual components of the compressor withoutintroducing sup plementary working procedures. This is due to the greatexactness by which the holes for such securing means for othercomponents can be cast.

Securing is achieved either by deforming the securing means in the holesprovided for them, or by deforming the surface of the holes themselves.Rivets, for exam ple, are suitable securing means because they, whenlocated in the holes, are clenched slightly, whereby the rivets are madeto bear against the inner surface of the holes, thus obtaining a lockingat right angles to the axis of the rivet shaft, whereas the locking inthe longitudinal direction of the rivet is taken over by the head of therivet.

Other securing means of this type are self-tapping screws. These screwsdeform by an insignificant cutting of the inner surface of the hole,thus obtaining a locking in the longitudinal direction as well ascrosswise.

In. this manner it is possible to obtain the same effect whichpreviously called for a supplementary working procedure, viz. cuttingthreads in the holes adapted to receive securing means.

With respect to the reduction of costs, it is advantageous not only tocast the motor support integrally with the cylinder, but also to includein the casting at least one mother chamber.

In particular, this is advantageous if the cast blank contains bothsuction and pressure muffler chambers. Uniting of the cylinder, themother and the motor support into one precision casting has theadvantage that these components can be relatively disposed in such manher that they reinforce the motor support.

By means of precision casting, it is possible to obtain thin walls, butthese thin walls would not be usable by 7 effective reinforcement toinsure adequate strength.

Further objects, features and characteristics of the invention will beapparent from the following detailed description or an embodimentthereof, and from the accompanying drawings, wherein, Y

FIG. 1 is an axial sectional view of a precision cast componentembodying features of the invention;

FIG. 2 is a front elevational view of the component shown;

FIG. 3 is a side elevational view of the component of FIGS. 1 and 2;

FIG. 4 is an enlarged fragmentary sectional view, as seen along the lineA-A in FIG. 2, showing a cover fastened to the casting by means of arivet; and

' FIG. 5 is a view corresponding to FIG. 4 but wherein the cover isfastened by means of a self-tapping screw.

. Referring to the drawings, and particularly to FIGS. 1 to 3, thecasting illustrated defines a collar 12 formed with a bearing 1 adaptedto guide the motor crank shaft of a motor compressor, and the stator ofthe motor is adapted to be connected with the collar 4 by securing meanspassing through holes 2 out through the reinforced Patented July 21,1964.

wall 3. In addition, the cylinder 5, including the piston chamber 6, isintegrally defined in the same casting, the central chamber 7 which isadapted to contain the crank is surrounded by a ring of muifierchambers8, the axiallyopen ends of which are adapted to be closed by means of acover 9. The holes 10 cut through the reinforced wall 11 of the collar12 are adapted to receive securing means for the cover 9.

In addition to the securing-means holes 2 and 10 extending parallel withthe bearing 1, other channels for interconnecting interior parts of thecasting, or other holes for connecting means can be provided and theseadvantageously originate in the front face 13 of the cylinder, and aresuitably located in corresponding reinforced walls 14. Thus, there areprovided the holes 15 for securing means for the valve plate (not shown)and the valve cover (not shown), and the connecting channels 16 betweenmuffier chambers 8 and the valve chamber (not shown). The recesses orgrooves 17, 18 and 19 are formed to receive valve-plate components. Thecollar unit illustrated is suitably cast by conventionalprecision-casting procedures, i.e., with extreme accuracy of form andsurface. Immediately after the casting, all connecting channels, e.g.16, and all holes for securing means, e.g., 2, 10, and 15, as well asall faces which bear against other parts, e.g. the front face of thebearing 1, of the surface 4, of the surface 12 and of the cylinder 5,are ready for use. Only the bores of bearing l and of cylinder need asmooth finishing, viz. correction of actual measurements in the amountof about 0.1 mm.

The connection between the component shown in FIGS. 1 to 3 and theadjoining parts, e.g. the cover 9, is shown in FIGS. 4 and 5, which showthe fastening of cover 9, which closes the open end of the crank casechamber 7 and the open ends of the muffler chambers 8. In FIG. 4, arivet 20 is inserted into the bore 10. During riveting, the rivet isclenched in such manner that at least part, and preferably all, of thesurface of the rivet bears against the surface of bore 19. In FIG. 5,the securing means for the cover 9 is a self-tapping screw 21 which,when screwed in, cuts its own thread in the surface of the bore 10. Thebore can also be a blind bore having a somewhat larger depth than thelength of the screw 21. In both cases, the component is secured bothaxially and radially without need for carrying out a special finishingof the precision case holes.

It will be understood that the present invention is concerned withimprovements in motor compressors of a known type and that many elementswhich serve to make up the complete motor compressor, and which form nopart of the present invention, e.g. the motor, the piston, the drivingconnections, the capsule, the suspension system, the valves, therefrigerant conduits, and the like, have been omitted from the drawingsand have not been described. A typical compresor of the type with whichthe invention is concerned is described, for example, in US. Patents2,285,754 and 2,836,349.

Similarly, while reference has been made to precision casting, and whileprecision casting is employed in the method of this invention, this is astandard casting procedure which is described, in Casting MethodHandbook Die Casting by C. 0. Herb (1958).

It is intended, therefore, that all matter contained in the foregoingdescription and in the drawings is to be interpreted as illustrativeonly and not as limitative of the invention.

The present application is related to my applications being filed oneven date herewith and entitled Motor Compressor for Small RefrigeratingMachines and Motor Compressor Especially for Small RefrigeratingMachines, and reference is made to these co-pending applications to showhow the motor and associated moving parts are combined with a castingcontaining the compressor cylinder and the muffler chambers.

posite to said bearing portion, a plurality of angularly spaced ribsextending longitudinally of said casting and radially outwardly of saidcompressor chamber defining a plurality of angularly spaced mufilerchambers disposed circumferentially of said compressor chamber, saidcasting comprising wall portions integrally with another tubular portiondefining a cylinder for a piston, said cylinder being disposedintermediate some of said muffler chambers in a circumferentialdirection relative to 7 said compressor chamber in communicationtherewith at one end and open at an opposite end, said casting comprsinginwardly thereof portions extending inwardly thereof closing in anddefining an inner end of said muffler chambers, each of said mufflerchambers having an open end opposite to said inner end and opening in acommon 7 direction corresponding to a direction in which said compressorchamber opens, and said collar comprising an annular collar integralwith said partitions and extending generally in an axial direction ofsaid casting.

2. A cast body component for a refrigeration compressor comprising anintegral casting having, a tubular bearing portion for rotatablysupporting a compressor crankshaft therein, wall portions defininganother tubular portion defining a compressor chamber substantiallycoaxial with said annular portion in communication with said tubularbearing portion and having an open end opposite to said bearing portion,a plurality of angularly spaced ribs extending longitudinally of saidcasting and radially outwardly of said compressor chamber defining aplurality of angularly spaced muffier chambers disposedcircumferentially of said compressor chamber, said casting comprisingwall portions disposed integrally with another tubular portion defininga cylinder for a piston, said cylinder being disposed intermediate someof said mufiier chambers in a circumferential direction relative to saidcompressor chamber in communication therewith at one end and open at anopposite end, said casting comprising inwardly thereof portionsextending inwardly thereof closing in and defining an inner end of saidmuffier chambers, each of said mufller chambers having an open endopposite to said inner end and opening in a common directioncorresponding to a direction in which said compressor chamber opens,said collar comprising an annular collar integral with said partitionsand extending generally in an axial direction of said casting, andbosses on said casting having axial holes therein for receivingfasteners for holding a plate closing said open chambers.

3. A cast body component for a refrigeration compressor comprising anintegral casting having, a tubular bearing portion for rotatablysupporting a compressor crankshaft therein, Wall portions defininganother tubular portion defining a compressor chamber substantiallycoaxial with said annular portion in communication with said tubularbearing portion and having an open end opposite to said bearing portion,a plurality of angularly spaced ribs extending longitudinally of saidcasting and radially outwardly of said compressor chamber defining aplurality of angularly spaced muffler chambers disposedcircumferentially of said compressor chamber, said cast 7 ing comprisingwall portions disposed integrally with another tubular portion defininga cylinder for a piston, said cylinder being disposed intermediate someof said mufiier chambers in a circumferential direction relative to saidcompressor chamber in communication therewith at one end and open at anopposite end, said casting comprising inwardly thereof portionsextending inwardly thereof closing in and defining an inner end of saidmuffler chambers, each of said muffler chambers having an open endopposite to said inner end and opening in a common directioncorresponding to a direction in which said compressor chamber opens, andsaid collar comprising an annular collar integral with said partitionsand extending generally in an axial direction of said casting, and saidcasting comprising a substantially flat surface circumferentially ofsaid open end of said cylinder.

4. A cast body component for a refrigeration compressor comprising anintegral casting having, a tubular bearing portion for rotatablysupporting a compressor crankshaft therein, wall portions defininganother tubular portion defining a compressor chamber substantiallycoaxial With said annular portion in communication with said tubularbearing portion and having an open end opposite to said bearing portion,a plurality of angularly spaced ribs extending longitudinally of saidcasting and radially outwardly of said compressor chamber defining aplurality of angularly spaced mufiler chambers disposedcircurnferentially of said compressor chamber, said casting comprisingwall portions disposed integrally with another tubular portion defininga cylinder for a piston,

said cylinder being disposed intermediate some of said mufiler chambersin a circumferential direction relative to said compressor chamber incommunication therewith at one end and open at an opposite end, saidcasting comprising inwardly thereof portions extending inwardly thereofclosing in and defining an inner end of said muffler chambers, each ofsaid mufiler chambers having an open end opposite to said inner end andopening in a common direction corresponding to a direction in which saidcompressor chamber opens, said collar comprising an annular collarintegral with said partitions and extending generally in an axialdirection of said casting, and a plate closing said open chambers.

References Cited in the file of this patent UNITED STATES PATENTS2,085,355 Greenwald June 29, 1937 2,285,754 Money June 9, 1942 2,505,709Goldberg et al Apr. 25, 1950 2,767,903 Warner Oct. '23, 1956 2,836,349Scheldorf May 27, 1958

1. A CAST BODY COMPONENT FOR A REFRIGERATION COMPRESSOR COMPRISING ANINTEGRAL CASTING HAVING A TUBULAR BEARING PORTION FOR ROTATABLYSUPPORTING A COMPRESSOR CRANKSHAFT THEREIN, WALL PORTIONS DEFININGANOTHER TUBULAR PORTION DEFINING A COMPRESSOR CHAMBER SUBSTANTIALLYCOAXIAL WITH SAID ANNULAR PORTION IN COMMUNICATION WITH SAID TUBULARBEARING PORTION AND HAVING AN OPEN END OPPOSITE TO SAID BEARING PORTION,A PLURALITY OF ANGULARLY SPACED RIBS EXTENDING LONGITUDINALLY OF SAIDCASTING AND RADIALLY OUTWARDLY OF SAID COMPRESSOR CHAMBER DEFINING APLURALITY OF ANGULARLY SPACED MUFFLER CHAMBERS DISPOSEDCIRCUMFERENTIALLY OF SAID COMPRESSOR CHAMBER, SAID CASTING COMPRISINGWALL PORTIONS INTEGRALLY WITH ANOTHER TUBULAR PORTION DEFINING ACYLINDER FOR A PISTON, SAID CYLINDER BEING DISPOSED INTERMEDIATE SOME OFSAID MUFFLER CHAMBERS IN A CIRCUMFERENTIAL DIRECTION RELATIVE TO SAIDCOMPRESSOR CHAMBER IN COMMUNICATION THEREWITH AT ONE END AND OPEN AT ANOPPOSITE END, SAID CASTING COMPRISING INWARDLY THEREOF PORTIONSEXTENDING INWARDLY THEREOF CLOSING IN AND DEFINING AN INNER END OF SAIDMUFFLER CHAMBERS, EACH OF SAID MUFFLER CHAMBERS HAVING AN OPEN ENDOPPOSITE TO SAID INNER END AND OPENING IN A COMMON DIRECTIONCORRESPONDING TO A DIRECTION IN WHICH SAID COMPRESSOR CHAMBER OPENS, ANDSAID COLLAR COMPRISING AN ANNULAR COLLAR INTEGRAL WITH SAID PARTITIONSAND EXTENDING GENERALLY IN AN AXIAL DIRECTION OF SAID CASTING.